Distribuição de mercúrio total em sedimentos da plataforma continental Amazônica: Brasil

Abstract

Este estudo foi desenvolvido na Plataforma Continental do Amazonas (PCA) com o objetivo de determinar os níveis de Hg total no sedimento de fundo, e assim contribuir como matriz ambiental indicadora para o plano geral de gerenciamento costeiro na região norte do Brasil. , estando dentro do intervalo de "background" referido para os rios amazônicos não contaminados, que é de 0,05 a 0,28 mg kg -1 . As concentrações de Hg no sedimento, especialmente no sedimento lamoso, mostraram uma estreita dependência com os teores de argila (material fino) e matéria orgânica, corroborando mecanismos geoquímicos importantes na dinâmica do metal. A maior adsorção do mercúrio pode estar associada ao aumento dos teores de compostos (óxidos e hidróxidos) de ferro, alumínio, manganês e os minerais primários e secundários formadores das rochas da bacia de drenagem amazônica. PalavRas-chave: elemento metálico; matéria orgânica; sedimento de fundo; geoquímica; Amazônia. . The mercury concentrations in the sediment bottom, especially in the mud sediment, had shown a narrow dependence with both the clay levels (fine material) and organic matter, corroborating important geochemical mechanisms in Hg dynamics. The largest adsorption of the mercury can be associated to the increase of the oxides and hydroxides compounds of iron, aluminum, manganese and others primary and secondary minerals from the rocks of the Amazon drainage basin. Distribution of total mercury in sediments from

Mercury in the Amazon basin: Human influence or natural geological pattern?

“…The sediments that compose ACS are the result of two distinct sources: a terrigenous source, which mixes both naturally occurring and chemically modified silt-clay sediments, predominantly deposited in the inner part of the platform, and another marine source of sandy sediments transported to ACS by Equatorial North Current and North Brazil Current, as demonstrated by Siqueira and Aprile (2012). The fluvial sediments accumulated in the ACS are predominantly of the Recent Quaternary, with sedimentation rates in the platform varying as a function of the ebb and flow cycles at the mouth of the Amazon River.…”

“…There is also interference from atmospheric forces as the Intertropical Convergence Zone, generating trade winds and rainfall, which determining the climatic seasons and the hydrological pattern of Amazonian rivers. According to Köppen-Geiger classification the climate of the region is "Am" hot and constantly humid (monsoon climate) for Marajó Bay, and "Af" equatorial for Amazon and Pará mouths, with a mean temperature of 28°C and rainfall exceeding 2000 mm year −1 , especially between the months of December and February (Siqueira and Aprile, 2012).…”

“…The sediments that reach the Amazon Continental Shelf (ACS) from the Amazon River basin are formed by muddy material rich in organic matter, which is eventually deposited mainly in the inner part of the shelf due to the strength of the ocean (Siqueira et al, 2004;Siqueira and Aprile, 2012;Siqueira et al, 2016). This characteristic of the environment in to accumulate finer sediments in the inner shelf has important consequences for the complexation of metals, especially Hg.…”

Ação do equipamento Bulbox – triturador de lâmpadas - no processo mitigatório dos impactos do mercúrio (HG) no meio ambiente

“…É um poluente orgânico persistente (POP); sendo assim, se dissemina desastrosamente chegando aos peixes e finalmente a outros animais e seres humanos de forma muito mais potencializada, pois foi observado que à medida que um agente é contaminado pelo mercúrio em um nível inferior na cadeia alimentar seu predador apresentará os níveis aumentados desse metal (BOENING, 2000;NEBEL et al, 2000); (SIQUEIRA et al, 2012).…”

<b>Heavy metal bioaccumulation of the characiform <i>Brycon falcatus</i> Muller & Troschel, 1844 in the Teles Pires basin, Southern Amazon

“…The majority of studies of heavy metals in the Amazon basin have focused on mercury contamination of fish (Malm, Branches, Akagi, Castro, & Pfeiffer, 1995;Dorea, Moreira, East, & Barbosa, 1998;Kehrig, Howard, & Malm, 2008), water (Lacerda et al, 1991;Roulet, Lucotte, Guimarães & Rheault, 2000), river sediments (Mascarenhas et al, 2004;Siqueira & Aprile, 2012), and humans Malm et al, 1995;Lebel et al, 1998;Khoury et al, 2013). Studies on Cr and Cu contamination in the Amazon basin are scarce, with few studies focusing on sediments (Silva, Ramos, & Pinto, 1999), water (Pinto et al, 2009;Lima et al, 2015), and fish (Lima et al, 2015).…”